Aerofoil structure and method of assembly

ABSTRACT

A structural assembly for an airfoil structure comprising at least one connection member configured to connect a leading-edge member, or a trailing-edge member, of an airfoil structure to a torsion-box member, such that the connection member prevents the leading-edge member, or trailing-edge member, from pivoting relative to the torsion-box member away from an operational position. At least one corresponding support is provided wherein the support is configured to be attachable to the connection member and further configured to be attachable to at least one system element.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the United Kingdom patent application No. 1710385.4 filed on Jun. 29, 2017, and of the United Kingdom patent application No. 1718997.8 filed on Nov. 16, 2017, the entire disclosures of which are incorporated herein by way of reference.

FIELD OF TECHNOLOGY

The present invention relates to a structural assembly, an airfoil structure and a method of assembly of an airfoil structure.

BACKGROUND OF THE INVENTION

Airfoil structures that are found in a variety of aircraft, spacecraft and wind turbine applications typically comprise a torsion box structural member, attached to a leading-edge structural member and a trailing-edge structural member. When a torsion box is applied to airfoil structures such as aircraft wings and stabilizers, it is often referred to as a “wing box.” A wing-box construction commonly used in commercial airliners includes a front spar member, a rear spar member, an upper cover member extending between the front spar member and the rear spar member, and a lower cover member extending between the front spar member and the rear spar member. One or more wing-box ribs may also be included between the spars and covers. Each of the front and rear spar members may be formed as a C-section with upper and lower flanges extending from an upstanding web. During assembly of the wing box, the upper and lower wing covers are usually attached to the flanges of the front and rear spar members. Fixed leading- and trailing-edge structural members such as the leading-edge D-nose (as opposed to moveable structures such as slat or flap devices), are then attached to the wing box by buttstraps attached to overhanging edges of the upper and lower cover members and/or attached to an upstanding web of each spar member.

The overall shape of fixed assembly must conform to a predefined shape as it is an airfoil structure. Any misalignment of various members may result in a shape deviation, which when operated in an aerodynamic flow, might result in unintended performance and handling qualities of the airfoil structure. Therefore, the exact final position of the various members relative to one another in the assembled product (i.e., when fixed in an operational position) is of critical importance throughout the assembly process. Variations in each member's dimensions from an engineering ideal (normally governed by manufacturing drawings) must be controlled within pre-determined angular and linear dimension limits. These limits are commonly referred to as engineering tolerances. The tolerances are estimated during the design of the airfoil structure taking into account the type of material and the manufacturing processes used for the various members. Deviations to tolerances are sometimes referred to as tolerance gaps. Rectification of tolerance gaps is normally required between the mating surfaces of the various members, which are difficult to access once the components are held in an installed position. Frequently this occurs in the position of the buttstraps, which then requires either partial or full structural disassembly of the airfoil structure, followed by the addition and/or removal of predetermined amounts of material from the out of tolerance members concerned. Normally the addition and/or removal is achieved through use of use of solid or liquid structural shims (also known as compensators) and/or component fettling. Component fettling may result in the members becoming non-standard parts. Similar deviations to tolerances are also common where system elements, e.g., electrical harness raceways and their associated support bracketry attach at various locations to the front or rear spar members or the fixed leading- or trailing-edge structural members and similar processes are used to correct these tolerance gaps until an acceptable fit and position of each system element to the airfoil structure is achieved. Normally, a large number of these system element support brackets are used in airfoil structures.

The processes to rectify tolerance gaps are therefore extremely time consuming and are a significant factor that affects the rate at which finished airfoil structures can be economically produced. It has therefore been proposed to remove buttstrap member attachment of leading-edge and/or trailing-edge structural members to prevent tolerance gaps in these areas. It is also proposed to introduce the use of modular leading-edge and/or trailing-edge members to the wing-box member, as well as associated modular system assemblies, in order to decrease the time overall required to assemble airfoil structures and the associated system elements. An airfoil structure design that enables a more efficient assembly process as well as optimizing the position where tolerance gaps can be rectified is therefore desirable.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a structural assembly for an airfoil structure comprising at least one connection member configured to connect a leading-edge member, or a trailing-edge member, of an airfoil structure to a torsion-box member, such that the connection member prevents the leading-edge member, or trailing-edge member, from pivoting relative to the torsion-box member away from an operational position; at least one corresponding support wherein the support is configured to be attachable to the connection member and further configured to be attachable to at least one system element.

A further embodiment of the present invention provides a structural assembly wherein at least one end of at least one connection member is configured to connect to the leading-edge member or the trailing-edge member or the torsion-box member using a lap joint.

Another embodiment of the present invention provides a structural assembly wherein at least one end of at least one connection member is configured to hingedly connect to the leading-edge member or trailing-edge member or the torsion-box member.

A further embodiment of the present invention provides a structural assembly wherein the length of at least one connection member is configured to be adjustable.

Another embodiment of the present invention provides a structural assembly comprising a plurality of system elements attachable at separate portions of each support to provide a torsional and/or bending stiffness about one or more axes of the structural assembly.

A further embodiment of the present invention provides a structural assembly wherein at least one system element is a pneumatic bleed air duct.

Another embodiment of the present invention provides a structural assembly wherein at least one system element is an electrical harness raceway.

A further embodiment of the present invention provides a structural assembly wherein no degree of freedom is permitted at the attachment between at least one support and at least one system element.

Another embodiment of the present invention provides a structural assembly wherein a rotational or translational degree of freedom is permitted between at least one support and at least one system element in order to allow the at least one system element to translate or rotate relative to the at least one support when attached.

A further embodiment of the present invention provides a structural assembly wherein at least one connection member and a corresponding support are provided as a single component.

Another embodiment of the present invention provides a structural assembly wherein at least one support comprises at least one attachment portion configured to be attachable to the corresponding connection member using at least one mechanical fastener.

A further embodiment of the present invention provides a structural assembly configured to span one or more rib bays.

Another embodiment of the present invention provides a structural assembly configured to partially span one or more rib bays.

A further embodiment of the present invention provides a structural assembly configured to span between 1 and 15 rib bays.

Another embodiment of the present invention provides a structural assembly further comprising an interchangeable aerodynamic panel positioned between the lower surfaces of the leading-edge member or trailing-edge member and the wing-box member, and wherein the interchangeable aerodynamic panel is removably attached to at least one connection member.

A further embodiment of the present invention provides a structural assembly provided in modular form.

Another embodiment of the present invention provides an airfoil structure comprising at least one structural assembly.

A further embodiment of the present invention provides an aircraft comprising an airfoil structure.

Another embodiment of the present invention provides a method of assembling an airfoil structure, the method comprising the steps of providing a torsion-box member comprising a spar web and a upper cover panel, providing a leading-edge member or trailing-edge member; positioning the leading-edge member or trailing-edge member at an installation position adjacent to the torsion-box member at the location of a pivot joint; connecting the leading-edge member or trailing-edge member to the torsion-box member at the pivotal joint; providing a structural assembly comprising a one or more supports attached to one or more corresponding connection members and one or more system elements attachable to the respective attachment portions of each support; positioning the structural assembly between the leading-edge member or trailing-edge member and the torsion-box member; rotating the leading-edge member or trailing-edge member about the pivot joint to an operational position; and fixing the leading-edge member or trailing-edge member in the operational position; fixedly connecting one or more connection members of the structural assembly to the leading-edge member, or the trailing-edge member, and the torsion-box member so as to prevent the leading-edge member, or trailing-edge member, from pivoting relative to the torsion-box member away from the operational position.

A further embodiment of the present invention provides a method further comprising the step of rotating the leading-edge member, or trailing-edge member, relative to the torsion-box member by adjusting the length of the connection member in order to compensate for a tolerance gap.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which:

FIG. 1 shows a frontal schematic view of an aircraft in an operational state;

FIG. 2 shows a top schematic view of the aircraft of FIG. 1;

FIG. 3 shows a schematic section view of the airfoil structure of FIGS. 1 and 2, taken through line A-A with a modular leading-edge member and wing-box member held in an installation position.

FIG. 4 shows a schematic section view of the airfoil structure of FIG. 3 with a modular fixed leading-edge member installed in a further installation position such that it is pivotable relative to a wing box.

FIG. 5 shows a schematic section view of the airfoil structure of FIG. 3 with a modular fixed leading-edge member fixedly attached in an operational position relative to a wing box.

FIG. 6 shows a schematic section view of the airfoil structure of FIG. 3 according to another embodiment of the present invention.

FIG. 7 shows a schematic section view of the airfoil structure of FIG. 3 according to a further embodiment of the present invention.

FIG. 8 shows a schematic cross section B-B of the pivot joint of FIGS. 4-7 according to an embodiment of the present invention.

FIG. 9 shows a schematic cross section B-B of the pivot joint of FIGS. 4-7 according to an alternative embodiment of the present invention.

FIG. 10 shows the airfoil structure of FIG. 3 according to a further embodiment of the present invention.

FIG. 11 shows a diagram for a method of assembling an airfoil structure according to embodiments of the present invention.

FIG. 12 shows a schematic isometric view of an airfoil structure according to a further embodiment of the present invention.

FIG. 13A shows the airfoil structure of FIG. 3 according to a further embodiment of the present invention.

FIG. 13B shows an exploded view of the airfoil structure of FIG. 13A.

FIG. 14 shows a schematic isometric view of an airfoil structure according to a further embodiment of the present invention

FIG. 15 shows a diagram for a method of assembling an airfoil structure according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, an aircraft 101 is shown with an airfoil structure 103 (also referred to as a wing) extending through approximately horizontally a fuselage 109. A further airfoil structure 105 (also referred to as the horizontal tail plane) extends approximately horizontally from either side of a rear portion of the fuselage 109. Yet a further airfoil structure 107 (also known as the vertical tail plane) extends vertically from an upper rear portion of the fuselage 109.

The aircraft 101 has a set of orthogonal aircraft axes. The longitudinal axis (x) has its origin at the center of gravity of the aircraft 101 and extends lengthwise through the fuselage 109 from the nose to the tail in the normal direction of flight. The lateral axis or spanwise axis (y) also has its origin at the center of gravity and extends substantially crosswise from wingtip to wing tip. The vertical or normal axis (z) also has its origin at the center of gravity and passes vertically through the center of gravity. A further pair of orthogonal axes is defined for the airfoil structure 103; a first axis 111 that defined by a major dimension of a leading-edge spar web 317 (see FIG. 3), and an orthogonal second axis 113 defined by a minor dimension of the leading-edge spar web 317.

With reference to FIG. 2, the airfoil structure 103 comprises a set of high-lift devices called leading-edge slats 203, which are mechanically connected to it at the leading-edge region 204. The airfoil structure 103 also comprises a set of high-lift devices called trailing-edge flaps 205, which are mechanically connected to it at the trailing-edge region 206. The slats 203 and flap 205 are moveable (i.e., non-fixed) devices, being actuatable during operation between a fully deployed position and a fully retracted position according to the inputs of a pilot. The purpose of the slats 203 and flaps 205 is to increase the camber and chord length and overall surface area of the wing 103 when deployed, thereby increasing the coefficient of lift that the wing 103 produces when required for slow flight of the aircraft 101. Adjacent to each slat 203 or flap 205 and/or in the areas where no high-lift devices are provided, the leading-edge and trailing-edge structure of the airfoil structure 103 is fixed, i.e., not configured to be moveable like the slats 203 and flaps 205 during operation of the aircraft 101. Similarly, the vertical tail plane 107 and the horizontal tail plane 105 each comprise their own respective leading edges 209, 211, trailing edges 213, 215 and fixed structure.

With reference to FIG. 3, a section view A-A of the airfoil structure 103 in the leading-edge region 204 is shown in an installation state that corresponds to an embodiment of the present invention. It should be appreciated that a similar view for the trailing edge would be substantially the same except reversed and comprising a different aerodynamic shape. The leading-edge structure is provided as a modular assembly, that is, a unitary preassembled structural module called a modular leading-edge member 301. The modular leading-edge member 301 may also be pre-equipped with systems and/or actuation elements of the slats 203. The use of pre-assembled unitary modules is desirable at this installation stage as it allows tolerance gaps to be controlled between a reduce number of components, which reduces the time overall required to assemble airfoil structure 103. It should be appreciated that the same advantages would apply to a modular trailing-edge member.

The modular leading-edge member 301 is held in an installation jig separately from a wing-box member 303 (not shown). The wing-box member 303 can also be referred to as a torsion-box member. The wing-box member 303 is held in a jig position (jig not shown) that supports the wing-box member 303 in a desired operational aerodynamic shape. The modular fixed leading-edge member 301 comprises a leading-edge skin member 305 fixedly attached to at least one leading-edge rib 306. The leading-edge skin 305 member is formed from aluminum sheet and is bonded to an outer facing flange of the leading-edge rib member 306 such that it defines the desired aerodynamic shape of the leading edge region 204 of the wing 103 at the section A-A when it is in the operational position (not yet shown). The leading-edge rib 306 is formed from composite material however it may be constructed from any other suitable material means, e.g., milled as a single piece from a billet of aviation grade aluminum alloy. It should be appreciated that the modular leading-edge member 301 is a single unitary assembly and therefore as such it may comprise any number of leading-edge rib members 306 and skin members 305 provided they are an assembly as such.

The leading-edge rib 306 defines an inner concave portion 307 that extends in a direction substantially parallel to the aircraft vertical axes (z) at a lower portion and extends in a direction substantially parallel to the aircraft longitudinal axes (x) at an upper portion. The lower portion of the leading-edge rib 306 terminates in an aft extending flange 309. The upper portion of the leading-edge rib 306 terminates in an aft extending clevis 311. The clevis 311 may alternatively be a single lug element known as a tang. The leading-edge rib 306 also comprises an upper portion that forms a cavity 312 between the leading-edge skin 305 and the rib 306 in the region of the clevis 311. The leading-edge skin 305 in the area of the cavity 312, which is the rearmost portion 313 of the leading-edge skin 305, tends inwards towards the clevis 311 when in an unstressed state, as is the case in the first installation position shown. In an operational position, the desired position of the rearmost portion 313 relative to the rest of the leading-edge skin 305 is shown by line 315. A spanwise stiffening element 316 is attached to the lower surface of the rearmost portion might. The stiffening element 316 provides additional strength and stiffness to the rearmost skin portion 313 between leading-edge rib member 306 in the modular assembly in order to reduce skin deformation when in the airfoil structure is subjected operational aerodynamic loading.

The wing-box member 303 comprises a single piece composite front spar web 317, upper cover 319 and lower cover 321. The upper cover 319 and lower cover 321 define the outermost aerodynamic surfaces of the wing-box member 303. The front spar web 317 extends between the upper cover 319 and lower cover 321 and defines the spar minor axis 113, which extends substantially in the same direction as the aircraft z axis in this example. A lower wing-box flange 323 extends forwards in a first direction of flight and a second direction along the spar major axis 111. An upper recess 325 is defined by the forward most portion of the upper cover 319. The aft most position of the upper recess 325 defines the limit of aerodynamic surface provides by the upper cover 319. Similarly, a lower recess 327 is defined by the forward most portion of the outermost surface of wing-box member 303 and the aft most position of the lower recess 327 defines the limit of aerodynamic surface provides by the lower cover 321. The wing-box member 303 is further provided a bracket that comprises a tang 329. The tang 329 corresponds in dimensions to the clevis 311 and is configured to fit between the clevis 311 when the modular leading-edge member 301 is installed to the wing-box member 303. Both the tang 329 and clevis 311 each define a bore 331 of the same diameter dimension. Each bore 331 is configured to receive a straight bush 332 with an inner diameter (not shown). Each bush 332 may be manufactured from a corrosion resistant material, e.g., brass or steel. It should be appreciated that the clevis 311 and tang 329 may be provided in reverse, e.g., the clevis 311 could be provided by a bracket on the wing box 303.

In the present embodiment, the axis of the bore 331 and corresponding bush 332 are concentrically aligned so as to define a pivot axis 333 that is aligned substantially parallel to the major axis 111 (shown FIG. 2) of the spar front spar web 317.

With reference to FIG. 4, a section of the wing 103 shown in FIG. 3 in the leading-edge region is shown in a further installation state, whereby the modular leading-edge member 301 is positioned at an angle relative to the wing-box member 303 such that the inner diameter of the bushes 332 in the tang 329 and clevis 311 are concentrically aligned. A pin 401 corresponding to a close clearance fit with this inner diameter dimension defined by each bush 332 is then inserted to form a pivot joint 403. The use of a pin 401, clevis 311 and tang 329 as a pivot joint 403 is advantageous in that it permits tolerance gaps to be corrected at a single location in a more straightforward manner How the correction of tolerance gaps can be achieved at a pivot joint 403 is described later in more detail with reference to FIGS. 8 and 9.

In the present embodiment the pin 401 comprises a head at a proximal end and a threaded portion at a distal end that is configured to receive a corresponding threaded torque nut (not shown). When the threaded torque nut is not fully installed, the pivot joint 403 permits 1 degree of rotational freedom about the pivot axis 333 of the modular leading-edge member 301 relative to the wing-box member 303. The rearmost portion 313 of the leading-edge skin 305 may be configured so as not to contact the wing-box member 303 in the further installation state. This may help with insertion of the pin 401 as a pre-tension load of the rearmost portion 313 will not need to be reacted. Once the threaded pin 401 is inserted, the modular fixed leading-edge member 301 is pivoted in the clockwise direction shown around the pivot axis 333 defined by the pivot joint 403 that is provided by the assembly of the clevis 311, tang 329 and threaded pin 401, i.e., the modular leading-edge member 301 would pivot about the pivot joint 403 substantially parallel to a plane formed by the aircraft x axis and the minor axis 113 of the spar web 317. The above-mentioned orientation of the pivot axis 333 is advantageous in that it provides airfoil structure assembly principle that is beneficial for removal of the modular leading-edge assembly 301 when the aircraft 101 is in service. Furthermore, the pin 401 and the pivot joint 403 are predominantly loaded in shear when the airfoil structure 103 is subjected to operational aerodynamic and inertial loading, which is structurally more efficient, thus leading to a lightweight design with a high load bearing capability.

It should be appreciated however that, in some instances the orientation of airfoil structure, e.g., for the vertical tail airfoil structure 105 and/or assembly principle, e.g., vertical airfoil structure assembly, it may be desirable for the pivot joint 403 to be arranged such that the pivot axis 333 is substantially parallel to a minor axis 113 of the spar web 317, i.e., the modular leading-edge member 301 would pivot about the pivot joint 403 substantially parallel to a plane formed by the aircraft x axis and the major axis 111 of the spar web 317.

With reference to FIG. 5, a section of the wing 103 in the leading-edge region is shown in an operational state. Having rotated the modular leading-edge member 301 about the pivot joint 403 to the jig position 501 indicated, a nut is then fully installed at the distal end of the threaded pin 401 and torqued to provide a compression means that is configured to compress the clevis 311 against the tang 329. The applied compression creates sufficient surface frictional forces between the tang 329 and clevis 311 such that it prevents the modular leading-edge member 301 from pivoting (rotating) relative to the wing-box member away from the operational position. In such a state, the modular leading-edge member 301 becomes fixedly attached to the wing-box member 303 at a position corresponding to the jig position 501. This results in an open type of airfoil structure 103 where a gap 505 is provided between the lower region of the modular leading-edge assembly 301 and the wing-box member 303 ahead of the front spar web 317. This gap 505 may be closed to form a continuous outer aerodynamic profile by attaching a removable aerodynamic panel 1001 which is described in more detail later with reference to FIG. 10. It should be noted that the jig position 501 is calibrated to the required operational position of the modular leading-edge member 301 relative to the wing-box member 303 and variations from this jig position 501 between the member 301 and 303 are tolerance gaps that need to be rectified.

The open type of airfoil structure 103 according to the present embodiment may be particularly advantageous where improved levels of accessibility are required to the interior of the airfoil structure 103 for certain spanwise positions or indeed along the entire span. It may also be particularly advantageous where large system equipment components such as high lift device actuation components need to be accommodated within the airfoil structure 103.

The attachment of the modular leading-edge member 301 to the wing-box member 303 in the above prescribed manner avoids the use of any buttstrap attachment of leading-edge and/or trailing-edge structural members. Seeing as the clearance between the pin 401, clevis 311 and tang 329 are more adaptable than for example buttstraps, it should be considered that the use of a pivot joint 403 therefore permits a type of connection of two unitary members that accommodates rectification large tolerance gaps in a straightforward manner. Furthermore, if tolerance gaps are identified between the modular leading-edge member 301 and the wing-box member 303, then the pivot joint 403 can be disassembled in order to adjust the connection much more easily than, for example, using a buttstrap member that requires repositioning of the members 301 and 303 if a tolerance gap needs to be rectified. Therefore, an airfoil structure 103 is provided that is easier and less time consuming to assemble.

During rotation of the modular leading-edge member 301, the rearmost portion 313 of the leading-edge skin 305 bears against the recess 325, and deforms to a pre-stressed state indicated by the line 315, such that the rearmost portion 313 substantially conforms to the recess 325. This is advantageous as it provides a simpler assembly and interface of the leading-edge skin 305 with upper cover 319, with no need for drilling and bolting to a buttstrap in multiple spanwise positions. This also results in a precisely controlled overlap of the modular leading-edge skin 305 with the upper cover 319 that reduces as much as possible physical steps in the outer aerodynamic shape between the members 301 and 303. In consideration of the above, this aspect of the airfoil structure 103 design is particularly advantageous for airfoil structures where laminar aerodynamic flow properties are desired.

With reference to FIG. 6, another embodiment of the present invention substantially the same as that of FIG. 5 is provided, with the exception that compression induced friction forces between the clevis 311 and tang 329 of the pivot joint are not used to prevent rotation of the modular leading-edge member 301 relative to the wing-box member 303. Instead, a connection member 601 is used separately from the pivot joint to prevent the modular leading-edge member 301 from pivoting relative to the wing-box member 303 away from the operational position. The connection member 601 fixedly attached to the modular leading-edge member 301 to the wing-box member 303. As the connection member 601 will transfer loads, it may allow for the pivot joint 403 to be sized to a lower load level therefore reducing the size, weight and complexity of the pivot joint 403.

The connection member 601 may be in the form of an adjustable strut comprising a cylinder 605 formed of a metallic material that has a threaded inner surface that is threadably engaged with a pair of threaded rod ends 603. At least one rod end is required. A first rod end 603 is hingedly connected to a corresponding lug 602 formed by the leading-edge rib 306. A second rod end 603 is also connected in a similar manner to a lug 602 formed by the spar web 317. The rod ends 603 are threaded in a direction opposite to one another, so that rotation of the cylinder portion in one direction increases the length of the connection member 601 and decreases the length in another. The use of an adjustable strut as the connection member 601 may be used advantageously to make small adjustments to the position of the modular leading-edge member 301 relative to the wing box 303 about the pivot joint 403. In such a way, it may be used to compensate for tolerance gaps or make relatively small adjustments of the position of the modular leading-edge member 301 relative to the wing-box member 303. Alternatively, the connection member 601 may be in the form of a non-adjustable strut. The strut may be in the form of a solid rod.

The connection member 601 may be placed as far as possible from the pin 607 and in an orientation that allows the connection member 601 to be principally loaded in tension and/or compression (if the pivot joint 403 were to exist between the lower portions of the modular leading-edge member 301 and wing-box member 303). The present embodiment may be advantageous because the orientation of the connection member 601 is adaptable due the positioning of the lugs 602. This means the orientation of the connection member 601 can be suited to the principal load direction requirements, which may vary along the span of the airfoil structure 103.

A further difference in the present embodiment to that of FIG. 5 is the use of a different type of pin 607 in the pivot joint 403. The pin 607 comprises a smooth shank extending along the majority of the length of the pin 607. The pin 607 is configured to allow 1 rotational degree of freedom about the bore 331, the clevis 311 and tang 329, but is not configured to compress the pivot joint when fully installed. One end of the pin 607 has a head that rests against the clevis 311 (or an underlying spacer) when installed. The pin 607 is secured in place between the clevis 311 and tang 329 using a split pin secured in a castellated nut attached at its other end. The use of a split pin arrangement allows for the pin 607 to be quickly secured in the pivot joint 403.

With reference to FIG. 7, an alternative embodiment of the present invention is provided that is substantially the same as that shown FIG. 6, with the exception that a connection member 701 is formed from a rod of substantially rectangular or circular cross-section machined from an aviation grade aluminum alloy material. For higher load applications or to ensure material compatibility, titanium alloy or corrosion resistant steel material may be used. Such a connection member 701 may be more suitable in circumstances where higher principal loads are expected to be carried by the connection member 701 between the modular leading-edge member 301 and the wing-box member. Similar to the previous embodiment of FIG. 6, the connection member 701 is also used as a means to prevent the modular leading-edge member 301 from pivoting relative to the wing-box member 303 about the pivot joint 403 away from the operational position.

Lap joints 703 connect each respective end of the connection member 701 to the modular leading-edge member 301 and the wing-box member 303, respectively. At the forward end, the lap joint 703 is formed by the connection member 701 that is mechanically fastened by a plurality of threaded fasteners 707 to the aft extending flange 309 of the modular leading-edge member 301. At the aft end, the lap joint 703 is formed by the connection member 701 mechanically fastened by a plurality of threaded fasteners 709 to the lower wing-box flange 323 of the wing-box member 303. The overlap in the lap joint 703 may be configured such that the length of the connection member 701 between mechanical fastened positions can be adjusted in order to compensate for tolerance gaps, which is advantageous for the reasons previously stated.

With reference to FIG. 8, an alternative embodiment applicable to any of the previously mentioned embodiments is provided. The interface between the clevis 311, tang 329 and pins 401 or 607 may be adjustable to remove manufacturing or assembly tolerance gaps by using one or more linear compensators 801 in the pivot joint 403. This is particularly advantageous for using in airfoil structures 103 predominantly formed from composite materials where linear tolerance gaps in the order of +−10 mm between parts may need to be corrected.

In the present embodiment, an eccentric bush 801 is used as a linear compensator to compensate for a combined linear tolerance gap substantially in the x and z direction between the modular leading-edge member 301 and the wing-box member 303. A further linear compensator 803, formed from a substantially flat brass plate material of specified dimensions, is also used to compensate for a single linear tolerance gap in the direction of the spar major axis 111 between the modular leading-edge member 301 and the wing-box member 303. It should be appreciated that any suitable alternative to the above types of linear compensator may be used, e.g., an eccentric bolt/washer combination may be used instead of an eccentric bush.

With reference to FIG. 9, yet a further alternative embodiment applicable to any of the previously mentioned embodiments is provided. The interface between the clevis 311, tang 329 and pins 401, 607 (depending on the chosen type) may be adjustable to remove angular tolerance gaps by using one or more angular compensators 901 in pivot joint 403. This is particularly advantageous for using in airfoil structures 103 predominantly formed from composite materials where angular tolerance gaps in the order of +/−1 to +/−1.5 degrees between parts may need to be corrected. In the present embodiment, a spherical bearing replaces the bush 332 normally installed in the tang 329 and acts as an angular compensator 901 to compensate for an angular tolerance gap between the modular leading-edge member 301 and the wing-box member 303 at the location of the tang 329. It should be appreciated that any suitable alternative to the above types of angular compensator may be used, e.g., a set of spherical washers may be used instead and may be installed at each side of the tang 329 between the clevis 311. While the loading bearing capability of spherical washers is lower than that of a spherical bearing, they may be suitable for lower loaded applications and they are generally cheaper than spherical bearings. Furthermore, they may be easier to install in the pivot joint 403, even with the pin 401 removed and the tang 329 and clevis 311 held in an installed position.

With reference to FIG. 10, a further embodiment of the present invention is shown that is applicable to any of the embodiments so far described. An aerodynamic panel 1001 is shown positioned between the lower surfaces of the modular leading-edge member 301 and the wing-box member 303. The outermost surface 1003 aerodynamic panel 1001 aligns with the outermost surface of airfoil structure 103 such that a smooth aerodynamic outer surface is achieved. The aerodynamic panel 1001 is formed of a stiff carbon fiber reinforced composite material however it may be formed from any other equivalent material, e.g., aluminum alloy. The aerodynamic panel 1001 is removably secured to the connection member 701 by means of a plurality of close fit mechanical fasteners 1005 that are threadably engaged with a corresponding set of captivated anchor nuts 1007 attached to an interior surface of the connection member 701. The use of captivated anchor nuts allows for a panel 1001 that is interchangeable and can be installed and replaced quickly during assembly or in-service. The aerodynamic panel 1001 may also be secured by mechanical fasteners in the same manner to the aft extending flange 309 and the lower wing-box flange 323. It should be appreciated that the fairing 1001 may also be secured to a plurality of connection members 701 extending in a spanwise dimension.

With reference to FIG. 11, a method of assembling an airfoil structure 103 comprises the steps of 1101—providing a torsion-box member 303 comprising a spar web 317 and a upper cover panel 319, 1103—providing a leading-edge member or trailing-edge member 301, 1105—positioning the leading-edge member or trailing-edge member 301 at an installation position adjacent to the torsion-box member 303 at the location of a pivot joint 403; 1107—connecting the leading-edge member or trailing-edge member 301 to the torsion-box member 303 at the pivotal joint 403; 1109—rotating the leading-edge member or trailing-edge member 301 about the pivot joint 403 to an operational position; and, 1111—fixing the leading-edge member or trailing-edge member 301 in the operational position. Optionally, the method of assembly may include the steps of 1113—providing a connection member 601, 701, and 1115—fixedly connecting the connection member 601, 701 to the leading-edge member, or the trailing-edge member 301, and the torsion-box member 303 so as to prevent the leading-edge member, or trailing-edge member 301, from pivoting relative to the torsion-box member 303 away from the operational position. Further the method of assembly may optionally include the step of 1117—rotating the leading-edge member, or trailing-edge member 301, relative to the torsion-box member 303 by adjusting the length of the connection member 601, 701 in order to compensate for an angular tolerance gap.

While all of the embodiments previously discussed describe to a modular leading-edge member 301 connected to a wing-box member at a single pivot joint 403, it should be appreciated that more than one of any combination of the pivot joints shown in FIGS. 5,6 and 10 may be provided for a given modular leading-edge member 301. By way of example with reference to FIG. 12, a pivot joint 403 may be provided by a clevis 311 pin or tang 329 arrangement (not shown) at each leading-edge rib 306 position between the modular leading-edge member 301 and the wing-box member 303. Furthermore, each pivot joint 403 may comprise linear compensators 801 and/or angular compensators 901 that may or may not be pre-attached (not shown) substantially in accordance with FIGS. 8 and 9. Pre-attachment may be particularly desirable where tolerance gaps are predetermined in the airfoil structure 103 prior to assembly.

With reference to FIG. 13A, yet a further embodiment of the present invention is provided, wherein, the airfoil structure 103 comprises a structural assembly 1300. The assembly 1300 comprises a support 1301 that is attached to a corresponding connection member 1302 and to a pair of system elements 1309.

The functions and form of the connection member 1302 are the same as those previously described in each of the previous embodiments, however in the present embodiment it is additionally configured to be attachable to the corresponding support 1301 and when so attached, to hold the support in a fixed position relative to the connection member 1302, as shown.

As can be seen from FIG. 13A, when the connection member 1302 is installed, the support 1301 (to which it is attached) is configured to project into an interior spanwise extending volume 1312 within the airfoil structure 103, which exists between the inner concave portion 307 of at least one rib 306 of the leading-edge member 301 and the spar web 317 of the torsion-box member 303, and to support the system element 1309.

The support 1301 comprises a substantially planar body formed of aerospace aluminum alloy that is orientated parallel to the connection member 1302. Aluminum alloy is preferable due to its strength, stiffness and relatively low cost, however the support may alternatively be made from any other suitable metallic material, e.g., titanium or non-metallic material, e.g., as an aerospace grade composite material such as CFRP, which may be preferable where higher strength, stiffness is required for a given weight.

Attachment of the support 1301 to the connection member 1302 is provided by a plurality of spanwise extending attachment portions in the form of lugs 1303 located at a lower end the body of the support 1301. At least one or more than two lugs may be used. Each lug comprises a lowermost surface that conforms to an interior facing surface portion of its connection member 1302. Each lug 1303 forms a straight-cut bore of fixed diameter that receives a threaded end of a countersunk head type mechanical fastener 1304, which passes through a corresponding concentrically aligned bore formed by the body of the connection member 1302. A similar fastener 1304 is used at each lug position. The fastener 1304 is secured by a locking-nut (or any suitable alternative, e.g., captivated anchor nuts), that engages the threaded end of the mechanical fastener 1304 and bears upon the upper surface of the respective lug 1303. Threaded attachment of the connection member 1302 to the support 1301 permits a more damage tolerant design and may allow one of the other to be removed or installed separately.

Alternatively, the attachment portion may be in the form of a flange integrally formed and extending along the lower edge of support 1301. This may be particularly suitable for higher load application or where permanent swaged fasteners may be used. Lugs may be preferable as they permit easier access to the mechanical fasteners during installation and removal. Alternatively, it may be desirable to provide a support 1301 that is bonded or welded permanently or integrally formed with the connection member 1302 so as to provide a single component that may be easier to manufacture, install or maintain.

The support 1301 is further provided with a pair of system elements attachment portions; 1305 positioned at an upper portion of the support 1301; and, 1307 positioned at a rearward facing portion of the support 1301. Each attachment portion 1305, 1307 is configured to receive and attach to a system element 1309, which in the present embodiment are a spanwise running, pneumatic bleed air duct attached at 1305 and an electrical harness raceway attached at 1307. The raceway is further fitted with electrical harnesses 1313 that interconnect with electrical consumers such as lights, pumps and sensors at various spanwise positions along the airfoil structure. Such an attachment principle may replace or be used in addition to system installation principles mentioned in previous embodiments whereby the modular leading-edge member 301 may also be pre-equipped with systems. It should be appreciated that alternatively one or more than two system elements 1309 may be used in the assembly 1300. It should also be appreciated that the type system element 1309 may also differ than the examples so far provided and may not be limited to pneumatic duct or raceway types of system elements, for example it may be that the support 1301 is attached to a one or more hydraulic fluid conduits or fuel conduits. The system elements 1309 are attached by mechanical fasteners to the attachment portions 1305 and 1307 such that the system elements 1309 are carried by the support 1301 in the interior spanwise extending volume 1312. In the present embodiment the attachment between the one or more of the system elements 1309 and the support 1301 is such that no degree of freedom, translational or rotational is given between the support 1301 and the system element 1309. Alternatively, one or more of the system elements 1309 may be attached to the support 1301 with a degree of freedom permitted to allow the system element 1309 to translate, e.g., in a spanwise direction, or rotate relative to the support 1301. This may be preferable for installation of system elements in airfoil structures that are design with a higher degree of spanwise bending, wherein induced loads to the system elements may need to be avoided.

The dimensions, stiffness and strength of the body of the support 1301 and the attachment means are sized by the positional separation requirements of the systems elements 1309 relative to adjacent structure or systems, as well as the static and dynamic systems load cases that the support 1301 and system elements 1309 are expected to be subjected to up to an airfoil structural ultimate load conditions.

Also shown in FIG. 13A is an aerodynamic panel 1306 that is removably secured to the connection member 1302 using a further pair of mechanical fasteners. The function of the aerodynamic panel 1306 is the same as previously described in other embodiments

In the present embodiment, it should be appreciated that the attachment principle of only attaching the systems elements 1309 to one or more supports 1301, which in turn are attached only to one or more connection members 1302, is advantageous in that any tolerance gaps caused by the systems elements 1309 shape are controllable and correctable by adjusting the overlap at the lap joint interface of the connection member 1302 to the flanges 309 and 323 of members 301, 303, respectively, prior to fixedly attaching them using mechanical fasteners 707, 709, as detailed in previous embodiments. Otherwise, such tolerance gaps would need to be controlled and corrected where the system elements 1309 are individually attached to the modular leading-edge member 301 and/or the wing-box member 303, which is more complex and therefore not as efficient to correct, and therefore more likely to slow the assembly process of the airfoil structure 103. This attachment principle reduces the likelihood of damage to the members 301, 303, and the system elements 1309 during their installation, which is desirable as such damage normally requires reworking that, can lead to higher manufacturing costs and delays in the overall assembly of the airfoil structure 103.

With reference to FIG. 13B, the structural assembly 1300 of FIG. 13A is shown removed from a leading-edge member 301 and a torsion-box member 303. As with previous embodiments, it should be appreciated that in the embodiment shown in FIGS. 13A and 13B, the orientation of the pivot joint 403 may be arranged in a different direction.

With reference to FIG. 14, a further embodiment of a structural assembly 1300 is shown, wherein the structural assembly 1300 is provided in a modular, preassembled form comprising a plurality of supports 1301 attached to a corresponding plurality of connection members 1302 and to a plurality of system elements 1309 that attach to the respective attachment portions 1305, 1307 of each support 1301.

Similar to the embodiment of FIGS. 13A and 13B, one or more than two of the system elements 1309 may alternatively be attached to the support 1301 in the modular assembly 1300.

Furthermore, in the present embodiment shown in FIG. 14, the attachment between the one or more of the system elements 1309 and the support 1301 is such that no degree of freedom translationally or rotationally is permitted between the support 1301 and the system elements 1309. Alternatively, one or more of the system elements 1309 may be attached to the support 1301 with a degree of freedom permitted to allow the system element 1309 to translate or rotate in a spanwise direction relative to the support 1301, which may be preferable for the reasons previously described. The dimensions, stiffness and strength of the body of the supports 1301 is sized by the positional separation requirements of the systems elements 1309 relative to adjacent structure or systems, as well as the static and dynamic systems load cases that the support 1301 is expected to be subjected to up to an airfoil structure ultimate load condition.

The modular assembly 1300 may be configured to span the length of one or multiple rib bays. In the exemplary embodiment of FIG. 14, a pair of rib bays 1310 are spanned. Each rib bay 1310 is delimited by a pair of adjacent ribs 306 approximately 0.7 meter apart measured in the spanwise direction. Preferably the modular assembly 1300 spans up to 15 rib bays. A modular assembly 1300 configured to span up to 15 rib bays is advantageous in that it corresponds to the spanwise length available between airfoil structural components which normally project from the torsion-box member 303, e.g., pylons, high-lift movables, etc.

The modular assembly 1300 may alternatively, or additionally, partially span one or more rib bays 1310.

The attachment of the system elements 1309 to the plurality of supports 1301 gives the modular assembly 1300 a sufficient level of stiffness/rigidity and integrity such that allows it to be handled as single module during installation and/or removal without the need of a support jig tool. Preferably a plurality of system elements 1309 are attached at different portions of each support 1301 so as to provide required torsional and/or flexural stiffness about one or more axes of the modular assembly 1300, so to reduce the flexure of the modular assembly 1300 while being handled, e.g., movement during installation, removal or transportation. The system elements may be arranged to improve the rigidity of the modular assembly 1300 by taking advantage of the sectional area properties and stiffness of the system element 1309. For example, as shown in FIG. 14, the continuous circular sectional properties of the pneumatic duct 1309 along its length provides a system element with an omnidirectional bending/torsional stiffness about its axis and is preferably arranged at towards the center of the modular assembly to contribute to its overall rigidity. Similarly, the electrical harness raceway is provided with continuous rectangular sectional properties along its length, which further enhances the bending stiffness about its axis and further contributes to the stiffness of the modular assembly 1300. It should be appreciated however that a single system element 1309 may be sufficient to provide the required level of stiffness which when attached to form the modular assembly of sufficient rigidity and integrity. Alternatively, a jig tool may be used if the weight and/or dimensions of the assembly 1300 are such that the rigidity provided by the interconnection of its constituent parts is not sufficient. This may particularly apply for a modular assembly 1300 configured to span multiple rib bays 1310.

The exemplary structural assemblies 1300 of FIGS. 13A, 13B, and FIG. 14 may be incorporated advantageously in the method of assembling an airfoil structure 103 previously described, which comprises the steps of: 1101—providing a torsion-box member 303 comprising a spar web 317 and a upper cover panel 319, 1103—providing a leading-edge member or trailing-edge member 301, 1105—positioning the leading-edge member or trailing-edge member 301 at an installation position adjacent to the torsion-box member 303 at the location of a pivot joint 403; 1107—connecting the leading-edge member or trailing-edge member 301 to the torsion-box member 303 at the pivotal joint 403; 1315—providing a structural assembly 1300 comprising a one or more supports 1301 attached to one or more corresponding connection members 1302 and one or more system elements 1309 attached to the respective attachment portions 1305, 1307 of each support 1301; 1317—positioning the structural assembly 1300 between the leading-edge member or trailing-edge member 301 and the torsion-box member 303; 1109—rotating the leading-edge member or trailing-edge member 301 about the pivot joint 403 to an operational position; and, 1111—fixing the leading-edge member or trailing-edge member 301 in the operational position; 1319—fixedly connecting one or more connection members 1302 of the structural assembly 1300 to the leading-edge member, or the trailing-edge member 301, and the torsion-box member 303 so as to prevent the leading-edge member, or trailing-edge member 301, from pivoting relative to the torsion-box member 303 away from the operational position. Furthermore, where the connection member may for example be an adjustable length type connection member, e.g., an adjustable strut, then the method of assembly may optionally include the step of 1117—rotating the leading-edge member, or trailing-edge member 301, relative to the torsion-box member 303 by adjusting the length of the connection member 1302 in order to compensate for an angular tolerance gap.

The use of a modular assembly 1300 as described is advantageous in that it enables systems elements 1309 to be preassembled separate to the assembly operation of the leading-edge member or trailing-edge member 301 and the torsion-box member 303 and to be installed using an attachment principle that reduce the number of attachment positions where tolerances gaps need to be considered. This also enables the use of a more cost and time efficient assembly principle for the overall airfoil structure assembly. As previously described, fewer or additional system elements may be used and the system elements used may be system elements other than pneumatic ducts or electrical harness raceways, e.g., a hydraulic fluid conduit or a fuel conduit. Furthermore, system supports 1301 may also be configured to attach to adjustable or non-adjustable strut type connection members 1302. Any number of connection members may be used. As with the embodiment shown in FIG. 12, it is possible that more than one of any combination of the pivot joints 403 and connection members shown in FIGS. 5, 6 10 and 13A may be provided. In the present embodiment of FIG. 14, a pivot joint 403 is provided by a clevis 311 pin or tang 329 arrangement (not shown) at each rib 306 position between the modular leading-edge member 301 and the wing-box member 303. Each pivot joint 403 may comprise linear compensators 801 and/or angular compensators 901 that may or may not be pre-attached (not shown) substantially in accordance with FIGS. 8 and 9. As described in previous embodiments, pre-attachment may be particularly desirable where tolerance gaps are predetermined in the airfoil structure 103 prior to assembly.

Wherein the foregoing description, integers or members are mentioned which have known, obvious or foreseeable equivalents; then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, while of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority. 

1. A structural assembly for an airfoil structure comprising: at least one connection member configured to connect a leading-edge member, or a trailing-edge member, of an airfoil structure to a torsion-box member, such that the connection member prevents the leading-edge member, or trailing-edge member, from pivoting relative to the torsion-box member away from an operational position; at least one corresponding support wherein the support is configured to be attachable to the connection member and further configured to be attachable to at least one system element.
 2. The structural assembly according to claim 1, wherein at least one end of at least one connection member is configured to connect to the leading-edge member or the trailing-edge member or the torsion-box member using a lap joint.
 3. The structural assembly according to claim 1, wherein at least one end of at least one connection member is configured to hingedly connect to the leading-edge member or trailing-edge member or the torsion-box member.
 4. The structural assembly according to claim 1, wherein a length of at least one connection member is configured to be adjustable.
 5. The structural assembly according to claim 1, further comprising a plurality of system elements attachable at separate portions of each support to provide at least one of a torsional or bending stiffness about one or more axes of the structural assembly.
 6. The structural assembly according to claim 1, wherein the at least one system element is a pneumatic bleed air duct.
 7. The structural assembly according to claim 1, wherein the at least one system element is an electrical harness raceway.
 8. The structural assembly according to claim 1, wherein no degree of freedom is permitted at the attachment between at least one support and the at least one system element.
 9. The structural assembly according to claim 1, wherein a rotational or translational degree of freedom is permitted between at least one support and the at least one system element to allow the at least one system element to translate or rotate relative to the at least one support when attached.
 10. The structural assembly according to claim 1, wherein at least one connection member and a corresponding support are provided as a single component.
 11. The structural assembly according to claim 1, wherein at least one support comprises at least one attachment portion configured to be attachable to a corresponding one of the at least one connection member using at least one mechanical fastener.
 12. The structural assembly according to claim 1, configured to span one or more rib bays.
 13. The structural assembly according to claim 1, configured to partially span one or more rib bays.
 14. The structural assembly according to claim 1, configured to span between 1 and 15 rib bays.
 15. The structural assembly according to claim 1, further comprising an interchangeable aerodynamic panel positioned between lower surfaces of the leading-edge member or trailing-edge member and the torsion-box member, and wherein the interchangeable aerodynamic panel is removably attached to the at least one connection member.
 16. The structural assembly according to claim 1, provided in modular form.
 17. An airfoil structure comprising at least one structural assembly according to claim
 1. 18. An aircraft comprising an airfoil structure according to claim
 1. 19. A method of assembling an airfoil structure, the method comprising the steps of: providing a torsion-box member comprising a spar web and an upper cover panel, providing a leading-edge member or trailing-edge member; positioning the leading-edge member or trailing-edge member at an installation position adjacent to the torsion-box member at a location of a pivot joint; connecting the leading-edge member or trailing-edge member to the torsion-box member at the pivotal joint; providing a structural assembly comprising a one or more supports attached to one or more corresponding connection members and one or more system elements attachable to the respective attachment portions of each support; positioning the structural assembly between the leading-edge member or trailing-edge member and the torsion-box member; rotating the leading-edge member or trailing-edge member about the pivot joint to an operational position; and, fixing the leading-edge member or trailing-edge member in the operational position; fixedly connecting one or more connection members of the structural assembly to the leading-edge member, or the trailing-edge member, and the torsion-box member so as to prevent the leading-edge member, or trailing-edge member, from pivoting relative to the torsion-box member away from the operational position.
 20. The method according to claim 19, further comprising the step of: rotating the leading-edge member, or trailing-edge member, relative to the torsion-box member by adjusting a length of the one or more connection members in order to compensate for a tolerance gap. 